diff --git a/Controller/ConfigController.php b/Controller/ConfigController.php
index e118975..5a9d429 100644
--- a/Controller/ConfigController.php
+++ b/Controller/ConfigController.php
@@ -27,6 +27,7 @@ class ConfigController extends BaseController
                 'organon_tweaks_persistent_sort' => (int) $this->configModel->get('organon_tweaks_persistent_sort', 1),
                 'organon_tweaks_done_badge' => (int) $this->configModel->get('organon_tweaks_done_badge', 0),
                 'organon_tweaks_done_closes_task' => (int) $this->configModel->get('organon_tweaks_done_closes_task', 0),
+                'organon_tweaks_done_autosubtasks' => (int) $this->configModel->get('organon_tweaks_done_autosubtasks', 0),
             ),
             'errors' => array(),
         )));
@@ -49,6 +50,7 @@ class ConfigController extends BaseController
         $persistentSort = isset($values['organon_tweaks_persistent_sort']) ? 1 : 0;
         $doneBadge = isset($values['organon_tweaks_done_badge']) ? 1 : 0;
         $doneClosesTask = isset($values['organon_tweaks_done_closes_task']) ? 1 : 0;
+        $doneAutoSubtasks = isset($values['organon_tweaks_done_autosubtasks']) ? 1 : 0;
 
         if ($this->configModel->save(array(
             'organon_tweaks_always_comment_icon' => $alwaysCommentIcon,
@@ -64,6 +66,7 @@ class ConfigController extends BaseController
             'organon_tweaks_persistent_sort' => $persistentSort,
             'organon_tweaks_done_badge' => $doneBadge,
             'organon_tweaks_done_closes_task' => $doneClosesTask,
+            'organon_tweaks_done_autosubtasks' => $doneAutoSubtasks,
         ))) {
             $this->flash->success(t('Settings saved successfully.'));
         } else {
diff --git a/Helper/OrganonDoneHelper.php b/Helper/OrganonDoneHelper.php
index 8cd78c3..8967304 100644
--- a/Helper/OrganonDoneHelper.php
+++ b/Helper/OrganonDoneHelper.php
@@ -3,6 +3,7 @@
 namespace Kanboard\Plugin\OrganonTweaks\Helper;
 
 use Kanboard\Core\Base;
+use Kanboard\Model\SubtaskModel;
 
 /**
  * Done/Todo badge helper.
@@ -22,6 +23,8 @@ class OrganonDoneHelper extends Base
 {
     const DONE_KEY = 'organon_done';
     const CLOSES_KEY = 'organon_tweaks_done_closes_task';
+    const AUTOSUB_KEY = 'organon_tweaks_done_autosubtasks';
+    const ALLDONE_KEY = 'organon_subtasks_alldone';
 
     /**
      * Is this task Done? (mode-aware: closed status in close-mode, else the metadata marker)
@@ -47,4 +50,63 @@ class OrganonDoneHelper extends Base
     {
         return (int) $this->configModel->get(self::CLOSES_KEY, 0) === 1;
     }
+
+    /**
+     * Mark a task Done in the current mode. Idempotent -- a no-op if it is already Done. Close-mode
+     * closes the task; marker-mode sets the DONE_KEY metadata.
+     *
+     * @param int $task_id
+     */
+    public function markDone($task_id)
+    {
+        $task = $this->taskFinderModel->getById((int) $task_id);
+
+        if (empty($task) || $this->isDone($task)) {
+            return;
+        }
+
+        if ($this->closesTask()) {
+            $this->taskStatusModel->close((int) $task_id);
+        } else {
+            $this->taskMetadataModel->save((int) $task_id, array(self::DONE_KEY => 'on'));
+        }
+    }
+
+    /**
+     * Recompute whether the task's subtasks are ALL done and, only on the up-transition
+     * (was-not-all-done -> now-all-done), auto-mark the task Done. The last-seen all-done state is kept
+     * in ALLDONE_KEY ('on'/'off') to detect that edge -- so a manual unmark is honored (nothing
+     * re-fires) and title edits / refreshes never re-mark. Never auto-unmarks.
+     *
+     * @param int $task_id
+     * @param int $exclude_id  a subtask id to exclude from the counts (the row being deleted --
+     *                         EVENT_DELETE fires BEFORE the row is removed, so it still counts)
+     */
+    public function syncSubtasksDone($task_id, $exclude_id = 0)
+    {
+        $task_id = (int) $task_id;
+        $exclude_id = (int) $exclude_id;
+
+        $totalQuery = $this->db->table(SubtaskModel::TABLE)->eq('task_id', $task_id);
+        $doneQuery = $this->db->table(SubtaskModel::TABLE)->eq('task_id', $task_id)->eq('status', SubtaskModel::STATUS_DONE);
+
+        if ($exclude_id > 0) {
+            $totalQuery->neq('id', $exclude_id);
+            $doneQuery->neq('id', $exclude_id);
+        }
+
+        $total = $totalQuery->count();
+        $done = $doneQuery->count();
+        $allDone = $total > 0 && $done === $total;
+        $prev = $this->taskMetadataModel->get($task_id, self::ALLDONE_KEY, 'off') === 'on';
+
+        // Save the new state BEFORE marking: in close-mode markDone() -> close() -> closeAll() re-fires
+        // subtask events into this method; with the marker already 'on', that re-entry sees no
+        // transition and is a no-op (no loop).
+        $this->taskMetadataModel->save($task_id, array(self::ALLDONE_KEY => $allDone ? 'on' : 'off'));
+
+        if ($allDone && ! $prev) {
+            $this->markDone($task_id);
+        }
+    }
 }
diff --git a/Plugin.php b/Plugin.php
index be70e14..bc2da83 100644
--- a/Plugin.php
+++ b/Plugin.php
@@ -3,6 +3,7 @@
 namespace Kanboard\Plugin\OrganonTweaks;
 
 use Kanboard\Core\Plugin\Base;
+use Kanboard\Model\SubtaskModel;
 use Kanboard\Model\TaskModel;
 
 class Plugin extends Base
@@ -122,6 +123,28 @@ class Plugin extends Base
             // Bulk "Mark all as Done/Todo" entry in the column header dropdown (moved into the native
             // menu by relocate.js). Opens a two-button modal that confirms + picks the direction.
             $this->template->hook->attach('template:board:column:dropdown', 'organonTweaks:board/mark_all_item');
+
+            // Sub-tweak (opt-in): auto-mark a card Done when its LAST subtask is completed. On every
+            // subtask change, recompute all-done and mark Done only on the up-transition
+            // (state-comparison in the helper), so a manual unmark is honored -- nothing re-fires.
+            // Dispatcher direct (the plugin on() wrapper drops the event). DELETE fires before the row
+            // is removed, so its id is excluded from the recount.
+            if ((int) $this->configModel->get('organon_tweaks_done_autosubtasks', 0) === 1) {
+                $container = $this->container;
+                $sync = function ($task_id, $exclude_id = 0) use ($container) {
+                    $helper = new \Kanboard\Plugin\OrganonTweaks\Helper\OrganonDoneHelper($container);
+                    $helper->syncSubtasksDone((int) $task_id, (int) $exclude_id);
+                };
+                $this->dispatcher->addListener(SubtaskModel::EVENT_UPDATE, function ($event) use ($sync) {
+                    $sync($event['subtask']['task_id']);
+                });
+                $this->dispatcher->addListener(SubtaskModel::EVENT_CREATE, function ($event) use ($sync) {
+                    $sync($event['subtask']['task_id']);
+                });
+                $this->dispatcher->addListener(SubtaskModel::EVENT_DELETE, function ($event) use ($sync) {
+                    $sync($event['subtask']['task_id'], $event['subtask']['id']);
+                });
+            }
         }
 
         // Auto-managed shared custom filters (v1.5 "Show all tasks", v1.6 month filters, v1.7
@@ -175,7 +198,7 @@ class Plugin extends Base
 
     public function getPluginVersion()
     {
-        return '2.1.3';
+        return '2.2.0';
     }
 
     public function getPluginHomepage()
diff --git a/README.md b/README.md
index 164abc7..8829d11 100644
--- a/README.md
+++ b/README.md
@@ -142,6 +142,12 @@ recolored -- only the badge.
   open-only filter, but reappears if you clear the filter (or use the "Board: show all tasks" filter).
 - With that option **off**, the badge is an independent marker stored in task metadata
   (`organon_done`) that never touches the open/closed status.
+- **Auto-mark on subtasks (opt-in).** When every subtask on a card is completed, the badge flips to
+  Done automatically (honoring the mode above -- marker or close). It only nudges at the moment the
+  last subtask completes: recomputing all-done on each subtask change and acting only on the
+  not-all-done -> all-done transition, so if you then set the badge back to Todo it is respected (the
+  subtasks stay done -- the description may hold unfinished business). It never auto-reverts to Todo.
+  Off by default; enable it in the Done badge settings.
 - **Bulk per-column action.** The board column header dropdown gains a **Mark all as Done/Todo** entry
   (`Template/board/mark_all_item.php`, moved into the menu by `relocate.js`). It opens a single modal
   that both confirms and picks the direction -- **Mark all Done** or **Mark all Todo** -- then sets
diff --git a/Template/config/show.php b/Template/config/show.php
index ef8cc44..859ef59 100644
--- a/Template/config/show.php
+++ b/Template/config/show.php
@@ -70,6 +70,9 @@
 
         <?= $this->form->checkbox('organon_tweaks_done_closes_task', t('Marking Done also closes the task'), 1, isset($values['organon_tweaks_done_closes_task']) && $values['organon_tweaks_done_closes_task'] == 1) ?>
         <p class="form-help"><?= t('When on, "Done" means the task is closed (so it leaves the board unless you clear the status filter), and clicking Todo reopens it -- native Close/Open stay in sync. When off, the badge is an independent marker that never changes the open/closed status.') ?></p>
+
+        <?= $this->form->checkbox('organon_tweaks_done_autosubtasks', t('Auto-mark Done when the last subtask is completed'), 1, isset($values['organon_tweaks_done_autosubtasks']) && $values['organon_tweaks_done_autosubtasks'] == 1) ?>
+        <p class="form-help"><?= t('When every subtask on a card is done, flip the badge to Done automatically (honoring the mode above). It only nudges at that moment -- if you then set it back to Todo, that is respected (the subtasks stay done).') ?></p>
     </fieldset>
 
     <div class="form-actions">
diff --git a/VERSION b/VERSION
index 07db151..8ede066 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-OrganonTweaks v2.1.3
+OrganonTweaks v2.2.0